So Julian and Sean should sit together and work perhaps in a kind of "hand in hand". I believe that they could help each other because of the different medias and customer groups . . . Sean could give a hint and link to the board game (there could be people who could be insterested in the boardgame after having played the software). And Julian could do perhaps also . . . everything is better than carry your money to the lawyer and wasting time for such discussions instead of working, living and spending time with the family . . . .

007

There are only two truly infinite things, the universe and human stupidity; I am unsure about the universe.
--Albert Einstein

The first time I played End of Atlantis I had these thoughts in order:

- Is this a re-interpretation of the myth? (Earth=Atlantis, we must flee from global catastrophy?), then
- Wait ... this was so a board game.

I think I have played a board game like this but I dont remember if it was Julian's one, it was a while ago.

Later I found this topic and wow, Julian's game looks alot like yours.

I find it unlikely that independent development could have occured in this case. I mean come on.
I'm not making a legal argument, just one of respect.

Put the board game, or what ever your source was, in the credits: inspired by or what ever.
Think of it like referencing in an essay. It gives you a more legitimate standing in the eyes of the reader if you reference not only direct quotes but also uses of ideas from other sources.